A Response to the Deniers of Anthropogenic Global Warming

Tuesday, November 15, 2011
12:43 P.M.

In a nationwide survey of 1,010 American adults taken in May 2011, only 47% of Americans believed in human-caused climate change. In this blog post, I will provide indisputable evidence that our climate is getting warmer, and humans are the cause. Anthropogenic global warming theory is grounded in solid scientific evidence. Since 2007, no scientific body of national or international standing has maintained a dissenting opinion on climate change. The last body to hold a dissenting opinion was the American Association of Petroleum Geologists.

Americans are misinformed about climate change because the people they look up to hold onto incorrect assumptions about human-caused climate change. One of the most embarrassing statistics is that according to a 2010 CBS News Report, only 31% of television meteorologists believe in global warming. This is embarrassing and shameful for the meteorological community. Additionally, many contemporary politicians deny global warming to push their own economic and social agenda, and do so without any solid evidence to back it up.

First, I’ll explain some common climate myths, and I will debunk them with science.

MYTH #1: The climate has changed before, so it is impossible to tell whether humans are contributing to climate change.

This is one of the biggest myths in the climate change denial industry. The climate has certainly changed before, but it has always been in response to a certain external force. If the sun emits less radiation, the earth cools. If volcanoes emit particulate matter in the air, the earth cools at first, and then warms due to the greenhouse gases emitted by the same volcanoes. Currently, the atmosphere is experiencing an external force – the anthropogenic emission of greenhouse gasses, most notably carbon dioxide, into the atmosphere. In the past, an increase in carbon dioxide has led to an increase in temperature. In the future, we can expect the same thing to happen.

One of the ways we can correlate past external forces to changes in temperature is to look at ice cores. The diagram below shows some characteristics in ice cores from Vostok, Antarctica. In the graph below, the first blue graph shows Carbon Dioxide concentrations, the red graph shows average temperature, the light green graph shows Methane concentrations, and the light orange graphs show the relationship between O18, an isotope of Oxygen, and solar radiation. Looking at the graph, it seems like the most 018 appears when solar radiation is the highest. CO2 (Carbon Dioxide) and CH4 (Methane) are both greenhouse gasses, you can see a strong correlation between them and the average temperature of the earth.

Now, look at the current CO2 and CH4 measurements from the top of Mauna Loa.

The highest CO2 concentrations shown over the past 436,000 years are around 280-300 ppm. For September 2011, CO2 concentrations at Mauna Loa were 389 ppm. Vostok does not take current CO2 measurements.

Historical Methane values at Vostok reached slightly over 700 ppb at their peak, and now, they are 1800 ppb.

To wrap it up, climate change has happened before, but because we have evidence of how it happened, we can theorize how the changes we make in the earth’s atmosphere will affect the climate. Since we have added so many greenhouse gases to the atmosphere, and the ice cores show us that increased concentrations of greenhouse gasses are associated with warming, we can hypothesize that the Earth will warm.

MYTH #2: It’s the sun’s fault!

While the sun clearly plays a huge role in the temperature of the Earth, the sun’s solar radiation has, in recent times, stayed relatively constant. Meanwhile, the temperature of the Earth continues to rise.

Up until about 1980, the solar radiation and temperature of the Earth followed each other pretty closely. Since then, the temperature has increased significantly, even when the sun’s radiation has remained pretty much the same.

MYTH #3: It won’t get that bad.

Perhaps the scariest aspect of climate change is an effect known as positive feedback. In terms of global warming, positive feedback means that as the earth gets warmer, other effects will be triggered that will increase the warming further.

One example is an increase of water vapor in the atmosphere. Water vapor is by far the most potent greenhouse gas, and as the temperature warms due to our greenhouse gas emissions, more water will evaporate from the oceans, warming the atmosphere even further.

Another positive feedback is when snow melts. Snow reflects much of the Earth’s radiation back to space, but when the snow melts, this radiation is absorbed by the Earth, and the Earth warms. Take a look at how much sea ice has melted over the north pole in recent years. The melting of sea ice will only accelerate warming.

MYTH #4: There is no way to effectively forecast a warming climate because we can’t get next week’s forecast right!

The latter part of this statement is actually true, particularly here in Seattle when the word “snow” pops up in the weather forecasts. Heck, sometimes we can’t get next day’s forecast right. Climate models, however, forecast trends over time, not specific weather conditions at a specific time, and they have proven to be very effective in doing so.

The diagram below shows the three model simulations of the past 140 years compared the measured temperatures. Model a only shows the predicted temperature for the natural forces on our climate, such as solar radiation. Model b only shows the predicted temperature for the external forces than humans have imposed on the atmosphere. Model c combines the two. Model c is pretty darn accurate.

Now that we’ve established that climate models are pretty accurate, let’s look at some for the future.

These climate models vary because they are based upon different levels of greenhouse gasses emitted by humans into the atmosphere over time. If we really clean up our act, we will likely see a scenario akin to B1. If we do a little bit of work, but not a whole bunch, we will see a scenario similar to A1B. If we continue going the way we are now, we will see a scenario like A2. Most places see significant warming, especially the arctic. There is no cooling anywhere.

I also want to just brush on “global cooling” for a moment. Many of you have seen this movie…

It’s one of my favorite movies, but it is completely false. Basically, they saw that the change in salinity in the ocean due to the melting of polar ice caps will cause the North Atlantic Current to shut down. This will not happen. Studies show that the current actually gets stronger as the Earth warms. Yet another positive feedback!

MYTH #5: The Earth is no longer warming!

This is the last major myth I want to address, and it is one of the biggest misconceptions about global warming. Let’s take a look at a graph of average temperature anomalies for the Earth since 1950.

You can see that there are times where the Earth does not warm as much as others, and there are times when it even cools. Since 1998, the Earth’s temperature has remained relatively constant.

However,  you can see that there is a clear upward trend in temperature. Right now, since the effects of global warming are relatively weak compared to what they will be in the future, the natural climate cycles of the Earth tend to balance out anthropogenic global warming from time to time. Eventually, though, the forces of man-made climate change will overpower the natural variations of the Earth, and these periods will become shorter and less frequent.

If there is any good news about this, it is that the Pacific Northwest will be one of the last places to experience global warming because of its proximity to the Pacific Ocean. The warming here, however, will still be significant, especially as we near the 22nd century. The high resolution forecast models based at the UW have modeled changes in temperature for our specific region. Let’s take a look at them.

All of these maps show the predicted changes in surface temperature during the winter months from the 1990s to a specific decade in the future.

At first, the warming isn’t too significant.

Even at 2050, the warming isn’t too bad. The mountains are warming up faster than the lowlands because snow is melting on them and creating a positive feedback.

By 2090, though, the Pacific Northwest has warmed significantly. It’s pretty sobering.

These models also forecast the snowpack in the mountains. Take a look at the forecast water content of snow at Stampede Pass for several different time periods.

You certainly won’t be skiing at Snoqualmie Pass by the 2090s!

Ironically, the snowpack in the Cascades has stayed relatively constant the past 30 years or so. As anthropogenic global warming continues to grow in scope, though, we will see a clear downward trend that will accelerate over time.

I blasted through this post in less than two hours, as I am a busy college student and I have work to do. I apologize if I have any typos. I feel very strongly about the fact that humans are causing climate change, and this post is an attempt to provide substantial evidence to support my views. Global warming should not be a debate at this point. It is inevitable, and it will have serious repercussions throughout the world.

If you have any thoughts on this post, comment below! I look forward to hearing your opinions.

Thanks for reading this particular post, it means a lot to me!
Charlie